Exam Prep Ch.11 The Sun Our Extraordinary Star 14th Edition - Discovering the Universe 14e Test Bank + Answers by Neil F. Comins. DOCX document preview.
Chapter 11: The Sun: Our Extraordinary Star
Section: 11-1
1. The photosphere of the Sun is the
A) visible “surface” of the Sun.
B) middle layer of the Sun’s atmosphere.
C) region of convecting gases below the visible surface of the Sun.
D) core of the Sun, where the nuclear energy is generated.
2. What is the Sun’s photosphere?
A) envelope of convective mass motion in the outer interior of the Sun
B) lowest layer of the Sun’s atmosphere
C) middle layer of the Sun’s atmosphere
D) upper layer of the Sun’s atmosphere
3. Which of these does NOT help to explain why the photosphere is called the visible surface of the Sun?
A) The photosphere marks an abrupt change in the Sun’s density, which increases dramatically just below it.
B) Most of the visible light seen from the Sun originates within the photosphere.
C) Because of increased density below the photosphere, light originating there is unlikely to survive the journey out of the Sun.
D) The gas above the photosphere is too rarified to produce a significant amount of light.
4. What term is given to the visible “surface” of the Sun?
A) prominence
B) corona
C) chromosphere
D) photosphere
5. The thickness of the photosphere, or the visible “surface” of the Sun, is
A) about 4000 km.
B) about 50,000 km.
C) about 1 km.
D) about 400 km.
6. The temperature of the Sun’s photosphere is nearly
A) close to 1 million K.
B) about 10,000 K.
C) 5800 K.
D) 4300 K.
7. The approximate temperature of the visible surface of the Sun is
A) 10,000 K.
B) 2000 K.
C) 4300 K.
D) 5800 K.
8. How does the average density of the Sun compare with that of the planet Jupiter?
A) It is not possible to specify an average density for an object as large as the Sun.
B) The Sun is many times denser than Jupiter.
C) The Sun is considerably less dense than Jupiter.
D) The Sun has approximately the same average density as Jupiter.
9. If the temperature of the solar surface is 5800 K and Wien’s law for the peak wavelength of the spectrum of the Sun, assumed to be a blackbody, is given by max T = 2.9 106, with T in Kelvins and in nanometers (nm), what is the expected peak wavelength of light from the Sun?
A) 600 nm
B) 500 nm
C) 300 nm
D) 50 nm
10.
The brighter cells surrounded by dark, narrow boundaries making up the cellular pattern that completely covers the visible surface of the Sun are called
A) granules.
B) spicules.
C) sunspots.
D) filaments.
11. What is the explanation for the bright cells of photospheric gases that make up the cellular granulation pattern seen on the visible surface of the Sun?
A) The cells are the base of a circulation pattern that extends from the photosphere to the outer corona.
B) The cells are regions of nuclear energy generation in the Sun’s photosphere.
C) Each cell is a region of strong magnetic field, which compresses and heats the gas within it.
D) The cells are the tops of blobs of hot gas that have risen from the Sun’s convective zone.
12. The granular appearance of the surface of the Sun is evidence of what phenomenon occurring in or on the Sun?
A) cells of thermonuclear fusion just under the visible surface
B) rapid rotation of the surface layers producing swirls of gas
C) concentration and heating of ionized gas by regions of high magnetic fields
D) convective motion under the solar surface
13. Granulation on the surface of the Sun is caused by
A) differential rotation of the Sun.
B) nuclear fusion processes occurring just below the surface.
C) magnetic field disturbances above the solar surface.
D) convective currents carrying heat from beneath the surface.
14. The granulation observed on the photosphere of the Sun appears to be the result of
A) the Sun’s magnetic field.
B) convection currents.
C) differential rotation.
D) optical effects caused by the turbulence in the Sun’s atmosphere.
15. Granulation, or the mottled appearance of the whole solar surface, is an indication of what physical process at work in the Sun?
A) outflow of neutrinos from the interior
B) rapid rotation of the Sun
C) thermonuclear fusion of hydrogen in the Sun’s surface layers
D) convective motion of gases in the upper portion of the Sun’s interior
16. A typical granule on the surface of the Sun is
A) about 1000 km across and lasts for a few minutes.
B) a few thousand kilometers across and lasts for about two solar rotations.
C) about 30,000 km across and lasts for several hours.
D) only about 50 km across and cannot be seen from Earth without special equipment.
17. The centers of the granular cells on the surface of the Sun appear to be brighter than the edges of the cells because
A) higher magnetic field strength at the centers condenses and heats the gases there.
B) the centers are composed of gases that are different from the gases that compose the edges.
C) gases at the centers are more transparent than gases at the edges, allowing astronomers to view deeper and hotter layers.
D) the centers are hotter than the edges.
18. The Stefan-Boltzmann law indicates that the energy emitted per second per area of an emitting surface varies with the fourth power of the Kelvin temperature. Suppose the center of a granule on the Sun’s photosphere is 6000 K and the edges of the cell are 100 K cooler. About how much energy is emitted each second from each unit area on the edge compared with that from the center?
A) 10–8
B) 50%
C) 93%
D) 127%
19. The gas motions within granules on the solar surface are
A) upward in the centers of some cells and downward in the centers of others; the gas cools as it passes over the boundaries between cells.
B) upward in the bright cell centers and downward around the darker edges.
C) downward in the bright cell centers and upward around the darker edges.
D) almost nonexistent; the dark patterns represent a network of absorbing gases overlying the photosphere.
20. If granulation on the Sun’s surface is a result of convective motion below it, with material upwelling at cell centers and returning between the cells, what is the expected temperature distribution across a granular cell?
A) The center of the cell will be cooler than the edges.
B) The center of the cell will be hotter than the edges.
C) Alternate cell centers will be hot and cold, with the edges at an intermediate temperature.
D) The temperature will be uniform across the cell because the photosphere conducts heat readily.
21. Spectral lines observed in the granules seen at the center of the Sun’s disk are
A) split by the Zeeman effect due to the strong magnetic fields in the granule.
B) always redshifted because granules are caused by gas descending into the Sun from higher layers.
C) redshifted near the center of the granule and blueshifted near the edge of the granule.
D) blueshifted near the center of the granule and redshifted near the edge of the granule.
22. A typical Doppler shift in the center of a granular cell compared to the “rest” wavelength is 8.75 10–4 nm. Take the rest wavelength to be the Hα line of 656 nm. What is the corresponding material speed in the center of the cell?
A) 0.4 m/s
B) 0.4 km/s
C) 8.75 m/s
D) 875 m/s
23. Astronomers use the word “limb” to refer to what part of a celestial body?
A) edge
B) center
C) top
D) bottom
24. What type of intensity distribution is seen across the image of the visible Sun from center to edge?
A) image with uniform distribution except where active regions occur
B) image of uniform brightness right to the limb
C) limb darkening
D) limb brightening
25. When viewing the Sun’s disk in visible light, one sees less deeply into the Sun near the limb than at the center of the disk because of the interaction of the light with atoms of the gas. What conclusion can be drawn from the observation that the Sun appears less bright near the limb than it does at the disk center?
A) The light from the solar limb is redshifted because of solar rotation, and this phenomenon gives the appearance of cooler gas at the limb.
B) The temperature of the gas increases with increasing height in the solar atmosphere.
C) The light has to travel through more of the solar corona from the limb; hence, it is reduced in intensity and appears cooler.
D) The temperature of the gas falls with increasing height in the solar atmosphere.
26. What causes limb darkening?
A) The photosphere at the edge of the Sun’s surface is cooler than it is in the middle of the Sun’s surface.
B) The limb of the Sun is darker than the center because sunspots collect along the limb.
C) Light reaching Earth from the limb of the Sun originates in the higher, cooler layers of the Sun.
D) Convection within the Sun is more efficient laterally than it is vertically with the result that the middle latitude regions of the Sun’s surface are hotter than the poles.
27. The surface of the Sun near its edge appears dimmer and cooler than at the center of the disk when viewed in visible light because one sees
A) deeper into the Sun near the edge than at disk, and temperature increases with depth.
B) light from the edge that has had to pass through more of the absorbing chromosphere and corona and is thereby reduced in intensity.
C) less deeply into the Sun near the edge than at disk center, and temperature decreases with depth.
D) less deeply into the Sun near the edge than at disk center, and temperature increases with depth.
28. What is the reason that the edge of the Sun’s visible disk is darker than the center?
A) The gases near the edge are in regions where stronger magnetic fields inhibit the emission of light.
B) One sees more deeply into the Sun near its edge, and the gas is cooler at the deeper levels.
C) One sees into shallower layers of the Sun near the edge where the gas is cooler and so emits less light.
D) One sees into shallower layers of the Sun near the edge. Because the gas is less dense there, it emits less light.
29. If looking at the center of the Sun, one sees into the base of the photosphere at approximately 5800 K. If looking into the Sun nearer the edge, one might see as far as a layer above the base with a temperature of perhaps 5500 K. According to the Stefan–Boltzmann relation, what is the flux in the center of the solar disk compared to the flux near the edge?
A) 5500/5800 = 0.95
B) 5800/5500 = 1.05
C) (5800/5500)2 = 1.11
D) (5800/5500)4 = 1.24
30. The center of the disk of the visible Sun appears brighter than the edges because one sees
A) less radiation from the cooler chromosphere near the edges of the Sun.
B) into deeper and hotter layers at the center of the solar disk.
C) into deeper and cooler layers at the center of the solar disk.
D) a greater contribution from the corona of the Sun at the center of the disk.
31. The Sun is about 1000 times more massive than the planet Jupiter. Why, then, does it have about the same average density as Jupiter?
A) The Sun has a much weaker gravitational field than Jupiter.
B) The Sun also has about 1000 times Jupiter’s volume.
C) The Sun is rotating much faster than Jupiter, and the resulting centrifugal force helps to support the outer solar layers.
D) The Sun’s solid core is composed of hydrogen, which is less dense than Jupiter’s rocky core.
Section: 11-2
32. Compared with the photosphere, the solar chromosphere is
A) less dense but with a greater vertical extent.
B) cooler and with a greater vertical extent.
C) denser but with a narrower vertical extent.
D) hotter and with a narrower vertical extent.
33. What is the name of the layer of the Sun’s atmosphere that appears as a pinkish ring just outside the visible disk of the Sun during a total solar eclipse?
A) chromosphere
B) photosphere
C) convective zone
D) corona
34. The word “chromosphere” refers to a
A) dense, spherical interstellar cloud of glowing gas.
B) layer in Earth’s atmosphere just below the ionosphere.
C) layer in the Sun’s atmosphere.
D) light-emitting region just outside the event horizon of a black hole.
35. Where is the chromosphere on the Sun?
A) The chromosphere is the outermost part of the Sun’s atmosphere.
B) The chromosphere is the layer below the visible surface of the Sun, where convection begins.
C) The chromosphere is the visible surface of the Sun.
D) The chromosphere is the layer above the visible surface of the Sun.
36. The visible light coming from the solar chromosphere is dominated by light of what color?
A) indigo
B) blue
C) green
D) red
37. Until recent times, astronomers had to await a total solar eclipse to study the chromosphere. Why couldn’t an observer hold a coin in front of them to cover the solar disk and create an artificial “eclipse” that would permit them to study the chromosphere?
A) Refraction of light around the coin will cause light from the photosphere to enter the observer’s eye along with light from the chromosphere.
B) Light from the very rarified chromosphere is too weak to penetrate Earth’s atmosphere.
C) Scattering by Earth’s atmosphere will allow light from the photosphere to pass around the coin and enter the observer’s eye.
D) Even with electronic equipment, it is not possible to hold the coin steady enough against the apparent motion of the Sun to view only the thin chromosphere.
38. What is a spicule on the Sun?
A) bright arc of gas suspended above the edge of the visible disk of the Sun
B) long, thin, curved line of bright gas in the corona
C) small, bright cell in the photosphere
D) jet of rising gas in the chromosphere
39. Spicules on the solar surface are
A) jets of gas surging out of the photosphere of the Sun into the chromosphere, usually at supergranule boundaries.
B) intense eruptions from sunspot groups and active regions, associated with solar flares.
C) streams of solar coronal material, usually seen only during a total solar eclipse.
D) curtainlike structures hanging over sunspot regions.
40. What are spicules?
A) small but rapidly erupting gas jets in the atmosphere of the Sun
B) gas streams in binary star systems, where a neutron star is pulling material from its companion star
C) streams of gas in interstellar clouds, heated by hot, massive stars
D) filamentary networks of hot gas in supernova remnants
41. Where do spicules tend to occur on the Sun?
A) at the boundaries of supergranules
B) at the boundaries of granules
C) surrounding and between sunspots in sunspot groups
D) randomly over the surface of the Sun
42. Spicules in the chromosphere rise up from
A) the centers of sunspots.
B) the edges of granules.
C) the edges of supergranules.
D) random, constantly shifting locations on the photosphere.
43. Many images of the chromosphere are taken through a filter that allows only specific wavelengths to pass. One reason for this is
A) to block out all other wavelengths of light and allow through the prominent light of these wavelengths produced in the chromosphere.
B) to allow through the filter the background light at these specific wavelengths produced by the photosphere and thus show an effective contrast with the chromosphere.
C) to ensure that Earth’s atmosphere does not interfere with the image.
D) to block out light from the corona.
44. What is the name of a small jet of rising gas in the chromosphere of the Sun?
A) flare
B) spicule
C) prominence
D) granule
45. How are spicules formed in the Sun’s chromosphere?
A) Spicules are formed from material on the tops of granules “tossed” to higher altitudes by the oscillations of the Sun’s surface.
B) Spicules are formed from gas carried upward along with the magnetic field lines at the edges of supergranules.
C) Spicules form where the Sun’s twisted magnetic field lines break through the photosphere.
D) Spicules are the remnants or “stumps” of solar prominences that have broken free of the magnetic fields that confine them and have erupted out into space.
46. The typical speed of spicular material traveling outward from the photosphere in the direction of Earth is 20 km/s. What would be the observed wavelength of the Balmer H hydrogen spectral line emitted by this gas compared with that from stationary solar material?
A) There will be no shift since the light is emitted by hydrogen gas in both the spicule and the stationary solar material.
B) 0.044 nm longer than the H from stationary solar material
C) 0.000067 nm shorter than the H from the stationary solar material
D) 0.044 nm shorter than the H from stationary solar material
47. A supergranule on the Sun is
A) a large area of slowly rising and falling gas containing hundreds of ordinary granules.
B) another name for a large, long-lived sunspot group.
C) a large area in which the rapid convection of the gas destroys all granules that would otherwise form in that area.
D) a very large but otherwise ordinary granule in the photosphere.
48. Large regions of the Sun’s chromosphere rise and fall vertically. These are called supergranules, and the boundaries of supergranules are marked by
A) vents.
B) sunspots.
C) spicules.
D) granules.
49. To what extent do spicules cover the chromosphere?
A) The chromosphere is always completely covered by spicules.
B) Spicules cover most but not all of the chromosphere.
C) Spicules cover a few percent of the chromosphere.
D) Spicules are rare and only appear during the height of the solar cycle maximum.
50. Compared with the dimensions of a granule in the Sun’s photosphere, a supergranule in the chromosphere is
A) very much larger; the diameter of each supergranule spreads across about a million granules.
B) a little larger, by a factor of 2.
C) much larger, by a factor of about 1000.
D) larger, by a factor of 10.
51. What is a plasma?
A) region where the H line causes the Sun’s surface to glow red, like blood
B) region where the intense magnetic field has caused the Sun’s atoms to line up in a rigid array
C) gaslike mixture of ions and electrons
D) unusual mixture of charged particles in which the positives and negatives do not occur in equal numbers
52. What is a plasma?
A) material in which all the spectral lines exhibit Zeeman splitting
B) gas so dense that visible light will not penetrate it
C) state of matter consisting of electrons and ionized atoms
D) ring around the Sun’s equator caused by magnetic effects
Section: 11-3
53. Which layer of the Sun’s atmosphere has the greatest vertical thickness?
A) corona
B) chromosphere
C) photosphere
D) They are each about the same.
54. What are the names of the three layers in the Sun’s atmosphere, in order from lowest to highest distance from the center of the Sun?
A) corona, chromosphere, photosphere
B) photosphere, chromosphere, corona
C) photosphere, corona, chromosphere
D) chromosphere, photosphere, corona
55. In order of increasing depth into the solar atmosphere, what are the names of the three layers of the Sun?
A) corona, chromosphere, photosphere
B) photosphere, chromosphere, corona
C) chromosphere, photosphere, corona
D) photosphere, corona, chromosphere
56. What fraction of the Sun’s total emission, across all wavelengths, is produced by the corona?
A) one part in a trillion
B) one part in a million
C) one percent
D) about one-third
57. Which part of the Sun is the LEAST dense?
A) core
B) photosphere
C) chromosphere
D) corona
58. Where is the coolest region in the Sun?
A) just below the photosphere, in the convective zone
B) in the lower corona
C) in the lower photosphere
D) in the lower chromosphere
59. What is surprising about the atmosphere of the Sun?
A) The pressure of the Sun’s atmosphere, after dropping just above the photosphere, rises again to a value equivalent to that at the photosphere at the top of the chromosphere.
B) The density of the Sun’s atmosphere, after falling rapidly above the photosphere, rises again significantly in the chromosphere.
C) The temperature of the Sun’s atmosphere, after rising continuously from below the photosphere through the chromosphere, falls again suddenly in the corona.
D) The temperature of the Sun’s atmosphere, after falling above the photosphere, rises again to reach very high values high in the atmosphere.
60. What name is given to the outermost atmospheric layer of the Sun?
A) convective zone
B) radiative zone
C) corona
D) chromosphere
61. What is the corona on the Sun?
A) Sun’s inner atmosphere, just above the photosphere
B) large region beyond (outside of) the Sun’s atmosphere, filled with solar wind
C) region above the solar north and south poles, the Sun’s “crown”
D) Sun’s outer atmosphere
62. The total light emitted by the solar corona, which is seen MOST effectively during a total solar eclipse, is equivalent in brightness to
A) the average brightness of the night sky at a dark site.
B) the brightness of the full Moon, about one millionth as bright as the solar photosphere.
C) the average brightness of the Milky Way.
D) about one thousandth that of the solar photosphere.
63. The visible corona of the Sun is MOST effectively photographed
A) during lunar eclipses, when the sky is darker.
B) during solar eclipses.
C) over a period of a few years around times of maximum solar activity.
D) in spring and fall seasons because of the tilt of the spin axis of the Sun.
64. Which occurrence led astronomers to the conclusion that the temperature of the gases in the solar corona is very high?
A) detection of emission lines from highly ionized elements like iron
B) measurement of the brightness and spectrum of the continuum visible light from the corona during eclipses
C) direct measurements using space probes exploring the corona
D) observation of the effect of these gases on the planets Mercury and Venus
65. Which of these features appears in the spectrum of the solar corona and indicates very high gas temperatures?
A) intense emission lines from highly ionized atoms, such as iron
B) bright emission from the hydrogen Balmer line, H, at the red end of the spectrum
C) intense continuous emission in the infrared part of the spectrum
D) dark absorption lines from hydrogen, calcium, and iron on a continuous bright spectrum
66. What is the source of the X-rays emitted by the solar corona?
A) high-energy charged particles spiraling along the coronal magnetic fields
B) X-rays from the solar photosphere, scattered by ions in the corona
C) decay of radioactive nuclei in the coronal gases
D) high-temperature gas of the corona
67. The spectrum of the solar corona reveals emission lines that originate in atoms from which many electrons have been stripped. What conclusion can be drawn from this result?
A) The magnetic field intensity is high enough to drag electrons from the atoms.
B) The solar rotation speed at coronal height reduces the ability of atoms to retain electrons.
C) The pressure of the gas is sufficient to squeeze the electrons from the atoms.
D) The atomic collision energies and hence the gas temperatures are extremely high.
68. To what does the symbol Fe XIV refer?
A) compound of iron, xenon, iodine, and vanadium
B) iron atoms that have lost 15 electrons
C) iron atoms that have lost 14 electrons
D) iron atoms that have lost 13 electrons
69. Where would one expect to find heavy atoms like iron stripped of many of their electrons?
A) photosphere
B) chromosphere
C) corona
D) sunspots
70. The temperature of the corona of the Sun is
A) very hot, about 106 K.
B) about twice as hot as the photosphere, 12,000 K.
C) very cool because it is the farthest part of the Sun from the heat source.
D) about the same as that of the photosphere, 5800 K.
71. What is the temperature of the solar corona?
A) 50,000 to 100,000 K
B) 2000 to 3000 K
C) 5800 K
D) 1 to 2 million K
72. The corona of the Sun has a temperature that is
A) about 10 K because it merges with cold interstellar space.
B) noticeably less than the photosphere, between 1000 to 2000 K.
C) about 1 to 2 million K.
D) about the same as the photosphere, about 6000 K.
73. One particular feature of the solar corona is its
A) variation with time over periods of a few minutes.
B) very high temperature.
C) very uniform density and structure.
D) very cold temperature.
74. Why is the solar corona so much hotter than the photosphere?
A) Energy is carried upward through the chromosphere by disturbed and tangled magnetic fields.
B) The corona absorbs light from the photosphere very efficiently.
C) The density of the corona is low; following the laws of thermodynamics, the product of density and temperature is a constant.
D) Energy is carried upward through the chromosphere by convective gas motions.
75. What is the “transition zone”?
A) This is the boundary where the temperature drops between the photosphere and the interior.
B) This is the boundary where the temperature drops again moving from the photosphere to the chromosphere.
C) This is the boundary where the temperature drops from the chromosphere to the cold of outer space.
D) This is where the temperature climbs sharply in moving from the chromosphere to the corona.
76. The extremely high gas temperatures in the solar corona mean that this region is BEST observed at wavelengths of
A) X-rays.
B) visible light.
C) Balmer H light from hydrogen gas.
D) infrared light.
77. The bright X-ray image obtained of the solar corona when the Sun is photographed at this wavelength indicates that the gas temperature at these heights is
A) extremely high, above 106 K.
B) extremely low, much cooler than the photosphere.
C) about twice that of the photosphere.
D) about the same temperature as the photosphere.
78. The energy source that heats the low-density coronal gas to extremely high temperatures is MOST likely
A) conduction because the chromosphere and corona contain high densities of free electrons that facilitate conduction.
B) rearrangements within complex magnetic field structures that energize the ionized gas.
C) convective currents in the chromosphere that carry hot gas outward from the photosphere.
D) radiative heat from the photosphere that is strongly absorbed by highly ionized atoms such as Fe XIV.
Section: 11-4
79. How much mass will the Sun lose to space during its lifetime, through the solar wind?
A) a few thousandths of its total mass
B) only a few millionths of its total mass
C) well over one-half of its total mass
D) up to 25% of its total mass
80. What is the solar wind?
A) constant flux of photons from the Sun’s visible surface
B) material from the corona, accelerated out into space
C) storm of waves and vortices on the Sun’s surface generated by a solar flare
D) circulation of gases in the chromosphere, between the equator and the poles of the Sun
81. If the solar wind particles have speeds of 3 106 km/h, how long will it take for them to travel from the Sun to Earth?
A) 50,000 hours, or 2000 days
B) 5 hours, or less than 1/4 day
C) 0.5 hour, or about 30 minutes
D) 50 hours, or about 2 days
82. What is the solar wind?
A) storm of waves and vortices on the Sun’s surface generated by a solar flare
B) constant flux of photons from the Sun’s visible surface
C) circulation of gases between the equator and the poles of the Sun
D) Sun’s outer atmosphere streaming out into space
83. The solar wind is made up primarily of
A) electrons and He nuclei (the “ash” of nuclear fusion).
B) hydrogen nuclei, with very few electrons.
C) hydrogen nuclei and electrons, some He nuclei.
D) equal numbers of all light elements, up to oxygen but no electrons, because they are unable to escape the Sun’s gravity.
84. The heliosphere is the
A) region surrounding Earth, formed where its magnetic field repels the solar wind.
B) region in the solar interior within which low-frequency “5-minute” sound waves continuously bounce around.
C) solar atmospheric layer between the chromosphere and the corona.
D) protective region containing the Sun and planets created by the solar wind, which prevents penetration by much of the material from outside the solar system.
85. Astronomers have recently compared the relative abundances of different isotopes of neon found in Moon rocks with those found in the solar wind. What conclusion have they drawn?
A) The Sun is much younger than previously thought.
B) The Sun was much hotter in the past than was previously believed.
C) The Sun was much cooler in the past than was previously believed.
D) The Sun has maintained a much more constant temperature than was previously believed.
86. Which one of these was NOT a finding of the Genesis spacecraft mission?
A) The solar wind has a tail of solar wind gases which extends far outside the heliosphere.
B) The isotope abundances in the solar wind and in Earth’s atmosphere are not identical.
C) Neon in layers under the Moon’s surface has been altered by being bombarded by radiation from space.
D) The Sun has maintained a relatively constant temperature for a long period.
87. Other stars
A) have never been detected producing a solar wind.
B) produce their own stellar winds, but these are too weak to reach the vicinity of the solar system.
C) produce their own stellar winds, but most are prevented by the Sun’s heliosphere from reaching the planetary region of the solar system.
D) produce their own stellar winds, and these galactic cosmic rays contribute the bulk of the cosmic ray flux Earth receives.
88. The heliosphere is a bubble in space defined by the outflow of the solar wind. A recent discovery of the solar wind is that it is
A) rapidly expanding.
B) rapidly collapsing.
C) not spherical.
D) much hotter than previously believed.
89. The heliosphere
A) is spherical.
B) is mostly within the orbit of Mercury.
C) is the limit for solar wind gases moving out beyond the Sun.
D) is defined by the solar wind and the solar magnetic field.
90. The solar wind is
A) the flow of matter onto the Sun under gravitational attraction.
B) ionized hydrogen gas and electrons orbiting the Sun between its surface and the planet Mercury.
C) a violent, explosive expansion of specific regions of the Sun’s atmosphere at certain times.
D) a gentle flow of solar material, mostly protons and electrons, that is always moving outward from the Sun.
Section: 11-5
91. The Stefan–Boltzmann law indicates that the energy emitted per second per area of an emitting surface varies with the fourth power of the Kelvin temperature. Suppose the center of a sunspot on the Sun’s photosphere is 4000 K and the normal photosphere is about 6000 K. About how much energy is emitted each second from each unit area in the center of this sunspot compared with that from the normal photosphere?
A) 10–8
B) 0.20
C) 0.67
D) 0.98
92. Sunspots are
A) cooler, darker regions on the Sun’s surface.
B) the shadows of cool, dark clouds of matter hanging above the solar surface.
C) cooler regions of the Sun’s high corona.
D) hotter, deeper regions in the Sun’s atmosphere.
93. A typical sunspot group lasts
A) virtually forever.
B) about two months.
C) 11 years.
D) 22 years.
94. What is the structure of a typical large sunspot?
A) irregular dark area of uniform darkness
B) round region of uniformly dark photospheric surface
C) roughly circular, dark region with a lighter central area, like a bullseye
D) dark center surrounded by a less dark area
95. What is the average length of time from one maximum in the number of sunspots on the Sun to the next maximum?
A) 22 years
B) 7 years
C) 11 years
D) 4
years
96. How does the number of sunspots on the Sun vary with time?
A) The number of sunspots varies relatively regularly, with a period of about 11 years.
B) The number of sunspots varies irregularly, with no periodicity.
C) The number of sunspots increases and decreases with a precise period of 11.1 years.
D) The number of sunspots increases for about 11 years and then decreases again over the next 11 years.
97. What is the lifetime of a typical sunspot?
A) two months
B) an hour
C) 11 years
D) from a few years to a few decades
98. Sunspots appear dark because they
A) are coronal holes.
B) are cooler than the surrounding surface.
C) are regions from which the light is prevented from escaping by strong magnetic fields.
D) have a different chemical composition than the surrounding surface.
99. How does the temperature inside the umbra of a sunspot compare with the solar photosphere outside the sunspot?
A) The umbra is about 100 K hotter.
B) The umbra is about 4000 K cooler
C) The umbra is about 1500 K cooler.
D) They are about the same temperature, the umbra being an absorbing layer over the sunspot.
100. The umbra of a sunspot is about 1500 K cooler than the surrounding solar photosphere. How does the light from the umbra compare with the light from the rest of the photosphere?
A) The umbra and the surrounding photosphere both emit light of the same color and the same intensity (per square meter) because they are both in the photosphere.
B) The light from the umbra is bluer.
C) The light from both the umbra and the surrounding photosphere are the same color, but the umbra emits less light per square meter.
D) The light from the umbra is redder.
101. Sunspots are cooler than the rest of the Sun’s surface, sometimes by as much as 1500 K. What would be the peak wavelength of the radiation from the sunspot compared with that from the rest of the Sun?
A) The peak wavelength of the radiation from the sunspot would be longer than that from the rest of the Sun.
B) The peak wavelength of the radiation from the sunspot would be the same because the light still originates at the Sun.
C) The peak wavelength of the radiation from the sunspot would be shorter or longer than that from the rest of the Sun, depending on the position and motion of the spot.
D) The peak wavelength of the radiation from the sunspot would be shorter than that from the rest of the Sun.
102. If sunspots are cooler than the photosphere (by as much as 1500 K), what would be the peak wavelength in a sunspot spectrum compared with the peak wavelength of the photospheric spectrum?
A) shorter
B) either shorter or longer, depending on the magnetic field strength in the sunspot
C) same because the chemical composition is the same (hydrogen and helium)
D) longer
103. The average sunspot group on the solar surface will last for about
A) two rotations of the Sun.
B) more than ten rotations of the Sun.
C) one day.
D) one-half rotation of the Sun.
104. Which of these astronomers was the first to detect the rotation of the Sun by watching sunspot motions?
A) Halley, while watching his comet
B) Copernicus
C) Galileo
D) Ptolemy
105. Galileo observed the phenomenon of solar rotation in the early 1600s by
A) noting the periodic (monthly) variation of auroral disturbances, or northern lights.
B) watching bright regions of hydrogen gas drift across the Sun.
C) measuring the motion of sunspots across the solar surface.
D) measuring the Doppler shift of hydrogen spectral lines from the east and west limbs of the Sun.
106. The rotation of the Sun is
A) slowest at the equator, faster at mid-latitudes, and fastest near the poles.
B) fastest at the equator, slowest at mid-latitudes, and spinning up to intermediate speeds around the poles.
C) fastest at mid-latitudes, slower at the equator, and slowest near the poles.
D) fastest at the equator, slower at mid-latitudes, and slowest near the poles.
107. How can one characterize the rotation of the Sun?
A) differential rotation, with the equator rotating more slowly than the poles
B) in a banded pattern, with alternating bands of fast and slow rotation to produce the sunspots
C) differential rotation, with the equator rotating faster than the poles
D) like a solid body, with all parts rotating at the same rate
108. What is the rotation period of the Sun?
A) about 2 rotations per year
B) about 1 rotation per day
C) about 4 rotations per month
D) about 1 rotation per month
109. The equatorial regions of the Sun are seen to rotate with an approximate period of about
A) 1 year.
B) 15 days.
C) 33 days.
D) 25 days.
110. Which of these bodies does NOT experience differential rotation?
A) the Sun
B) Jupiter
C) Saturn
D) Mars
111. What is the character of the sunspot cycle?
A) Starting at sunspot minimum, new spots appear uniformly over the Sun, then gradually become concentrated at mid-latitudes as they increase and then decrease in number.
B) Starting at sunspot minimum, spots first appear far from the equator, followed by new spots closer to the equator as they increase in number, the latest spots closest to the equator.
C) Sunspots increase and decrease in number over 11 years, appearing at random locations between latitudes 10° and 30° from the equator in both hemispheres.
D) Starting at sunspot minimum, new spots appear close to the equator, followed by spots farther from the equator as they increase in number, the latest spots dying out at high latitudes.
112. Over the course of a sunspot cycle of about 11 years, the regions of sunspot occurrence on the Sun move
A) from the northern to the southern hemisphere or vice versa, across the equator, within the range of ±30° latitude.
B) from the poles to the equator.
C) poleward, moving from 10° to 30° latitude.
D) toward the equator, moving from 30° to near zero latitude.
113. Over the course of a typical sunspot cycle, the position of the appearance of new sunspots moves from
A) just poleward of the equator toward 30° N and 30° S of the equator.
B) latitudes of about 30° to a few degrees above the equator in both hemispheres.
C) the poles toward 30° latitude in both hemispheres.
D) about 30° N latitude, across the equator, to 30° S latitude.
114. How large is a typical sunspot?
A) It is about the size of Earth.
B) It covers about 10% of the visible hemisphere of the Sun.
C) It is about the size of Australia.
D) It is too small to see without the aid of a powerful telescope.
115. The year 2013 marked a sunspot maximum. What does this mean?
A) In that year the sunspots were considerably hotter than usual.
B) The typical age of a sunspot is considerably longer than usual.
C) More sunspots were seen that year than average.
D) The sunspots seen in that year were much larger than average.
116. Which of these bodies does NOT exhibit some differential rotation?
A) Moon
B) Sun
C) Jupiter
D) Saturn
Section: 11-6
117. The sunspot cycle on the Sun is a(n)
A) regular movement of a relatively constant number of sunspots from the poles to the equator of the Sun over an 11-year period.
B) somewhat irregular cycle of buildup and decay of sunspot numbers, averaging about 11 years and with a variable number of sunspots for each cycle.
C) extremely regular buildup and decay in the number of sunspots, with a precise period of 11 years but with widely varying numbers of sunspots
D) Extremely regular buildup and decay in the number of sunspots, with a precise period of 11 years with every cycle having the same number of sunspots at maximum.
118. The polarity of the Sun’s magnetic field reverses during a sunspot cycle. When does this reversal take place?
A) when the sunspot number is minimum, about every 11 years
B) when the sunspot number is minimum, about every 22 years
C) when the sunspot number is maximum, about every 11 years
D) when the sunspot number is maximum, about every 22 years
119. The major feature that distinguishes a sunspot from other regions on the Sun is
A) its very powerful magnetic field.
B) faster rotation around the Sun’s axis than neighboring regions.
C) its greater light emission compared with the photosphere.
D) a coronal hole existing above it.
120. What is the Zeeman effect?
A) generation of magnetic fields by the motion of charged particles
B) attraction of two areas of opposite magnetic polarity toward each other
C) inability of charged particles to move perpendicular to magnetic field lines
D) splitting of spectral lines emitted by atoms within a magnetic field
121. What is the Zeeman effect?
A) When a light source is moving relative to an observer, the wavelengths of its spectral lines are shifted to longer or shorter wavelengths.
B) When the temperature of a light source is increased, the wavelength of maximum emission decreases.
C) When a light source is located in a magnetic field, the emitted spectral lines are split into two or more components.
D) When light is focused on a metal surface, electrons are ejected from the metal only if the wavelength of the light is shorter than some critical wavelength.
122. The Zeeman effect describes the change in wavelength of emitted light caused by
A) the light passing through a transparent medium.
B) magnetic fields acting on the radiating atoms.
C) the atoms being in an extremely intense gravitational field.
D) relative motion of the source and observer.
123. What change in spectral lines emitted by atoms is described by the Zeeman effect?
A) broadening of the lines associated with the high temperature of the emitting gas
B) change in relative intensity of different lines from sources of different temperature
C) shift in the lines because of the movement of the source
D) splitting of lines because the atoms are within an intense magnetic field
124. The Zeeman effect refers to the
A) brightening of sunlight near sunspots.
B) shift of spectral lines because of the motion of the source of light.
C) splitting of spectral lines when magnetic fields are applied to atoms.
D) shift toward longer wavelength of spectral lines when the atoms are in a magnetic field.
125. Which of these statements about sunspots is NOT true?
A) Sunspots are cooler than the surrounding photosphere of the Sun.
B) Sunspots increase and decrease in number relatively regularly.
C) Sunspots often occur in pairs of opposite magnetic polarity.
D) Sunspots occur in regions of lower-than-average magnetic fields.
126. Intense magnetic fields have been found to exist in sunspots by the observation of what specific physical effect?
A) Zeeman effect, the splitting of spectral absorption lines
B) Doppler shift of light from sunspots
C) observation of ionized atoms in the region of the sunspots
D) measurement of the relative strengths of spectral absorption lines of gases in the sunspot
127. The strength of the magnetic field in a sunspot is estimated from Earth by
A) measuring the size and brightness of the sunspot.
B) measuring the size and mass of a prominence suspended above the sunspot.
C) measuring the shape of structures seen in the corona above sunspots during solar eclipses.
D) observing the wavelength splitting of atomic spectral lines by the Zeeman effect.
128. In 1908, George Ellery Hale noticed that the spectral lines from sunspots were split into closely spaced components, and he concluded that the magnetic fields in the sunspots must be very strong. What is the name given to this effect?
A) photoelectric effect
B) Hale effect
C) Doppler effect
D) Zeeman effect
129. An astronomer observing certain regions of the Sun through a spectrometer notices that the spectral lines emitted from these regions are split into two or more components. What does the astronomer conclude about these regions from his observations?
A) The regions contain fast-moving gas.
B) The regions are very hot.
C) The regions contain strong gravitational fields.
D) The regions contain strong magnetic fields.
130. Why are sunspots cooler than the rest of the Sun’s surface?
A) Sunspots, unlike the rest of the Sun, are made of plasma, and plasmas are difficult to heat.
B) Sunspots mark the pathways along which neutrinos escape from the Sun. Neutrinos move so quickly that they deposit very little energy along their paths.
C) Sunspots occur where the magnetic field lines return into the Sun carrying smaller amounts of heat energy from the thin solar atmosphere.
D) Sunspots mark the places where the magnetic field lines penetrate the Sun’s photosphere. The hot solar plasma beneath is repelled from these field lines and thus inhibits the flow of heat to the surface at these points.
131. How would one describe the Sun’s rotation?
A) The Sun rotates as a solid body, just like Earth.
B) The entire Sun experiences differential rotation, with the core rotating more slowly than the surface.
C) The entire Sun experiences differential rotation, with the core rotating more rapidly than the surface.
D) The outer layers of the Sun experience differential rotation, but the inner regions rotate as a solid body.
132. How does one describe the rotation of the Sun?
A) The Sun rotates as a single rigid object, much like Earth.
B) The equatorial region of the Sun rotates faster than the polar regions, and this differential rotation extends all the way through the core.
C) The equatorial region of the Sun rotates more slowly than the polar regions, and this differential rotation extends all the way through the core.
D) Differential rotation extends only partway into the Sun. The core rotates as a rigid body.
133. What is a typical magnetic field strength inside a sunspot?
A) a few times stronger than Earth’s magnetic field
B) a million times stronger than Earth’s magnetic field
C) about 1% of the strength of Earth’s magnetic field but still strong for low-density gases on the Sun
D) a few thousand times stronger than Earth’s magnetic field
134. Which of these statements about sunspots is NOT true?
A) Sunspots occur in regions of lower-than-average magnetic fields.
B) Sunspots increase and decrease in number relatively regularly.
C) Sunspots often occur in pairs of opposite magnetic polarity.
D) Sunspots are cooler than the surrounding photosphere of the Sun.
135. The major feature that distinguishes a sunspot from other regions on the Sun is
A) its faster rotation around the Sun’s axis than neighboring regions that actually produce the spot.
B) its very powerful magnetic field.
C) its much higher emission of light.
D) the coronal hole that always exists above it.
136. Sunspots are regions where the Sun’s magnetic field penetrates the photosphere. What holds each spot together?
A) the mutual attraction of the magnetic field lines
B) the attraction of the magnetic field lines for the plasma inside the sunspot
C) rapid circulation of plasma around the field region
D) gravitational attraction within the colder, more condensed gases within the spot
137. The magnetic field in a large rotating body can reverse direction periodically. For which two bodies in the solar system has evidence been found for such magnetic reversals?
A) Sun and Moon
B) Sun and Earth
C) Earth and Moon
D) Earth and Venus
138. The differential rotation of the Sun causes the magnetic fields in its interior to become tangled. According to the Babcock model of the solar activity cycle, what happens to these tangled magnetic fields?
A) These tangled fields finally merge into a single magnetic field emerging from the Sun’s north pole and entering the Sun’s south pole. This merging begins the 11-year solar cycle.
B) The magnetic fields stretch and thereby lose energy, which makes them lighter, and they float to the Sun’s photosphere, where they break through and form sunspot groups.
C) The tangled magnetic fields interrupt the convection currents and trap gas. The gas rises, carrying the fields with it, and floats to the Sun’s photosphere, where the field lines break through the surface and form sunspot groups.
D) These tangled fields alternately trap and release gases from the convection currents, leading to the periodic pulsations observed by helioseismology.
139. A model was proposed in 1960 by Horace Babcock to explain the solar cycle. This model bears the name
A) solar pulsation.
B) magnetic dynamo.
C) helioseismic.
D) Zeeman.
140. If the magnetic polarity of the north pole of the Sun at a particular time is N, what will be the polarity of the first spot to appear of a bipolar sunspot region rotating about the Sun in the northern hemisphere?
A) S
B) It is not possible to determine the polarity from the information given.
C) The polarity will depend on the latitude of the spot and will be N if greater than 30° latitude and S if less than 30° latitude.
D) N
141. Two pairs of associated sunspots appear on the visible disk of the photosphere of the Sun, one pair in each hemisphere. If the magnetic polarity of the westernmost spot in the northern hemisphere is found to be N, what will be the magnetic polarities of the other three spots?
A) The magnetic polarity of all the spots at this time will be N because polarity of sunspots changes only every 11 years.
B) The magnetic polarity of the other northern spot will be N, while in the two spots in the southern hemisphere it will be S.
C) The magnetic polarity of the other northern spot will be S, and the southern hemisphere spots will match this alignment; the westward spot will be N, while the eastward spot will be S.
D) The magnetic polarity of the other northern spot will be S, while in the southern hemisphere the westward spot will be S and the eastward spot will be N.
142. What is the average length of a complete cycle of sunspots and magnetic fields on the Sun?
A) 22 years
B) 7 years
C) 4.5 years
D) 11 years
143. Solar magnetic activity at the present time in history seems to vary almost periodically with a time scale of
A) 100 years.
B) 5 minutes.
C) 22 years.
D) 2 years.
144. What is helioseismology?
A) study of the Sun’s tidal effects in causing earthquakes
B) study of the Sun’s response to collisions with grazing comets
C) study of vibrations in the Sun’s interior
D) detailed study of the shape of the Sun
145. Evidence for a magnetic field reversal has NOT been seen for
A) the Sun.
B) other stars.
C) Earth.
D) Jupiter.
146. The Maunder minimum is the name given to the
A) unexpectedly low number of neutrinos observed from the Sun.
B) region of lowest temperature in the photosphere, between the decreasing temperature in the solar interior and the increasing temperature in the chromosphere.
C) period of 70 years in the 1600s and early 1700s during which essentially no sunspots were seen.
D) minimum in the number of sunspots that occurs roughly every 11 years.
147. One of the phenomena that accompanied the Maunder minimum in sunspot numbers during the late seventeenth and early eighteenth centuries was
A) a severe drought in western North America.
B) an unusual heat wave in Europe.
C) the Black Plague.
D) the onset of El Niño.
148. Mean temperatures in Europe during the Maunder minimum, when virtually no sunspots were seen between 1645 and 1715, were
A) more strongly fluctuating above and below the average temperature compared with the period from 1715 to the present.
B) unchanged, within statistical uncertainty.
C) higher than average.
D) lower than average.
149. Which recently discovered fact about the Sun might have some bearing on climate changes and the weather on Earth?
A) The Sun’s surface is oscillating up and down every 5 minutes.
B) There are far fewer neutrinos emitted from the Sun than predicted.
C) Solar wind seems to originate in cooler regions of the corona—the coronal holes—and their number varies month by month.
D) The Sun’s overall energy output depends on the 11-year sunspot cycle.
150. How does the Sun’s overall magnetic field behave?
A) The Sun does not have an overall coherent field but magnetic fields, and their polarity is centered on sunspots and randomly distributed over the Sun.
B) The northern and southern hemispheres have the same magnetic polarity, which reverses every 11 years.
C) The northern and southern hemispheres have opposite magnetic polarity, which reverses every 11 years.
D) The poles of the Sun have the opposite magnetic polarity from the equator, which reverses every 11 years.
151. What causes sunspots?
A) Magnetic fields below the photosphere pull gas down, creating holes in the photosphere.
B) Differential rotation on the Sun creates vortices, or eddies, that are cooler and darker than the rest of the solar surface.
C) Solar flares cause the photosphere to expand and cool in the vicinity of the flare.
D) Magnetic fields breaking through the photosphere inhibit gas motion where the field is strong.
152. Sunspots are caused by
A) the impact of meteoroids and comets on the solar surface.
B) differential rotation and its effect on magnetic fields just under the solar surface.
C) dark, absorbing clouds hanging over the surface, above the magnetic field regions.
D) coronal holes, which darken the surface.
153. The reason sunspots are cooler than the photosphere is that
A) they are points where streams of cool gas from the corona impinge on the photosphere, thereby cooling these regions.
B) their powerful magnetic fields inhibit the convective flow of the ionized gases of the photosphere.
C) they are holes in the photosphere that reveal the lower temperature gases in the deeper layers.
D) their powerful magnetic fields act on the atoms of the photosphere to prevent them from emitting light.
154. What is the cause of the sunspot cycle on the Sun?
A) Comets crashing into the Sun cool the photosphere and create sunspots. The 11-year sunspot cycle is the result of an 11-year periodicity in the flux of comets.
B) Subsurface magnetic fields are twisted by the Sun’s differential rotation and break through the surface as sunspots, then gradually cancel each other and return below the surface.
C) Differential rotation on the Sun creates eddies, or vortices, that cool the photosphere and create sunspots, then the eddies gradually cancel each other out and the cycle starts over.
D) Subsurface magnetic fields are concentrated by the Sun’s differential rotation. These fields remain under the surface and prevent heat from reaching the photosphere, creating sunspots. The concentrated fields gradually cancel each other out, and the cycle starts over.
155. How can astronomers BEST observe the 5-minute oscillations of the Sun’s surface?
A) Zeeman-effect measurements of magnetically sensitive lines
B) high-resolution positional observations of the edge of the solar disk
C) measurement of the modulation of radio emissions from the solar surface, similar to the modulation used to transmit sound signals by radio on Earth
D) high-precision Doppler shifts of spectral lines
156. One method that has been used successfully in recent times to investigate the deep interior of the Sun has been to observe
A) regular 5-minute oscillations and fluctuations of the surface.
B) the spectrum and behavior of a sunspot, whose roots are deep inside the Sun.
C) the progress of a solar-impacting comet.
D) physical conditions in the deep interior, using a spacecraft that penetrated into the Sun.
Section: 11-7
157. Which of these phenomena is NOT a characteristic of the peak period in the solar activity cycle?
A) increased surface temperature on the Sun and a measurable increase in the temperature of Earth’s atmosphere
B) increased solar flare activity with consequent disruption of radio communications on Earth
C) stronger magnetic field on the Sun and increased numbers of sunspots
D) enhanced aurora activity on Earth
158. Which of these is NOT considered to be a feature of the quiet Sun?
A) solar wind
B) sunspot
C) spicule
D) granule
159. A solar plage is a
A) cooler region of the photosphere surrounding the very cold central region of a sunspot.
B) brightening of a portion of the Sun in light from hydrogen and other atomic species, appearing just before sunspots.
C) “hole” in the hot corona through which solar wind escapes into interplanetary space.
D) gigantic loop of gas, lifted by magnetic fields above the solar surface, appearing dark against the photosphere and bright against dark space.
160. What is a plage?
A) sudden eruption on the photosphere in the vicinity of a sunspot group
B) region in the corona that looks bright against the darkness of space but dark against the brighter photosphere
C) bright area in the chromosphere
D) bright area on the photosphere
161. What causes plages?
A) compression and heating of chromospheric gas by magnetic fields
B) blobs of convecting gas rising through the photosphere and depositing their energy in the chromosphere
C) matter descending along loops of magnetic field in the corona
D) sunspots, which prevent heat from reaching the chromospheric gases above them, leading to cooler plage regions
162. Is there a connection between plages and sunspots?
A) No. Sunspots are a photospheric phenomenon, while plages occur in the chromosphere.
B) Yes. The magnetic fields that result in sunspots in the photosphere continue on up through the chromosphere where they produce plages.
C) Yes. The magnetic fields that result in sunspots in the photosphere compress the gases above the photosphere, and this pressure creates plages in the chromosphere.
D) Yes. The 5- minute oscillations of the photosphere push the sunspots up into the chromosphere every 5 minutes and thus results in plages.
163. Just before a sunspot forms on the photosphere, one will often see at that location
A) plages.
B) filaments.
C) prominences.
D) solar flares.
164. What name is given to a brighter region in the chromosphere, often in association with a sunspot?
A) filament
B) plage
C) granule
D) prominence
165. What name is given to an irregular dark line or streak often seen in H photographs of the solar photosphere, often associated with sunspots?
A) granule
B) spicule
C) filament
D) plage
166. What is the name given to a large loop of bright gas extending outward from the edge of the Sun (often seen during total solar eclipses)?
A) prominence
B) spicule
C) filament
D) plage
167. An arching column of gas suspended over a sunspot group is called a
A) coronal hole.
B) flare.
C) spicule.
D) prominence.
168. What is the difference between a “filament” and a “prominence”?
A) A filament is a crack in the photosphere, while a prominence is an outflow of gas into the corona.
B) Filaments are the openings through which charged particles escape the Sun to become the solar wind. Prominences are the clouds of charged particles on their way off the Sun.
C) Prominences are the outflow of particles from the Sun’s poles. Filaments are dark bands around the Sun’s equator.
D) Filaments and prominences are two views of the same phenomenon.
169. The Sun sends charged particles toward Earth where they contribute to the aurora. Which of these events does NOT contribute substantially to this outflow of particles?
A) coronal mass injections
B) sunspots
C) solar flares
D) filaments
170. Which of these phenomena on the Sun does NOT appear to be a source of particles traveling out into the solar system from the Sun?
A) spicules
B) eruptive prominences
C) coronal holes
D) flares
171. What is a filament on the Sun?
A) plage near the end of its life, when it is fading away
B) prominence seen in silhouette against the photosphere
C) dark sunspot that has been stretched by solar differential rotation
D) spicule seen in profile near the edge of the Sun’s limb
172. What is a prominence on the Sun?
A) large loop of gas supported by magnetic fields
B) jet of gas shot upward from an emerging sunspot
C) shock wave created by the eruption of a solar flare
D) another name for a plage
173. Filaments and solar prominences are part of the
A) convection zone.
B) photosphere.
C) chromosphere.
D) corona.
174. What is the name of a sudden, highly energetic, eruptive surge on the surface of the Sun?
A) prominence
B) sunspot
C) plage
D) flare
175. How long does a typical flare on the Sun last?
A) about a minute
B) 2 months
C) less than an hour
D) 5 days
176. Where on the Sun do solar flares most often occur?
A) in a narrow band along the solar equator
B) at the polar regions
C) in coronal holes
D) within sunspot groups
177. X-ray observations of the corona reveal lighter and darker spots, the latter indicating where the corona is cooler. These darker spots are the source of
A) granules.
B) spicules.
C) sunspots.
D) high-speed jets of gas flowing out of the Sun.
178. What are the MOST energetic eruptive events to occur on the Sun?
A) erupting prominences
B) coronal mass ejections
C) thermonuclear explosions
D) solar flares
179. Which of these is NOT a characteristic of coronal mass ejections?
A) contribute to auroras on Earth
B) disrupt radio communication
C) are the major source of hazardous solar particles
D) cease entirely during the years of solar minimum
180. Which of these events is NOT a consequence of a coronal mass ejection event from the Sun that is aimed toward Earth?
A) major health hazard for astronauts in orbit around Earth, particularly on the Moon
B) major hurricane
C) damage to and even destruction of satellite electronics and power systems
D) disruption to radio transmission and electrical power systems on Earth
181. How does a coronal hole compare with the rest of the solar corona?
A) cooler but brighter
B) hotter and brighter
C) cooler and darker
D) hotter but darker
182. A coronal hole shows up MOST prominently on what kind of photograph?
A) red light of the first Balmer line of hydrogen, H, at 656.3 nm
B) radio wavelengths
C) any wavelength of visible light
D) X-ray
183. The solar wind is almost entirely ionized gas
A) that escapes most easily through coronal holes.
B) that escapes most easily from X-ray–bright regions of the solar corona.
C) flung out mostly by solar flares.
D) flung out from the Sun’s equatorial region by the centrifugal force due to the Sun’s rotation.
184. Coronal holes are thought to be
A) conduits through which the solar wind can easily escape.
B) the primary source of dust released from the Sun.
C) fluctuation in human behavior (e.g., astrology).
D) powerful loops of magnetic fields, linked to active regions.
185. The solar wind appears to escape MOST easily from which regions of the Sun?
A) coronal holes
B) solar magnetic poles
C) all over the surface, with no preferred location
D) sunspots
186. The solar wind is strongest
A) near the solar equator, where solar spin reduces the gravitational field.
B) in flare explosions.
C) in sunspots.
D) in coronal holes, cooler, lower-density regions in the corona.
187. The solar wind is ionized gas flowing outward
A) from the Sun’s magnetic poles, where magnetic forces on the ionized plasma is lowest.
B) from sunspots.
C) more or less uniformly from the entire solar surface.
D) primarily through coronal holes.
188. If a solar flare produces an X-ray outburst and also triggers a coronal mass ejection (CME), what will be the arrival times of these components, referenced to the time of occurrence on the Sun?
A) The X-rays arrive within a few seconds of the flare, while the CME material arrives about an hour after the flare.
B) Disturbances on Earth from each of these components occur about 2 days after the flare.
C) The disturbances from these outbursts occur almost simultaneously on Earth, about 8 minutes after the flare, because the CME material travels almost at the speed of light.
D) The X-rays arrive about 8 minutes after the flare, while the CME material arrives after about 2 days.
Section: 11-8
189. Which of these statements describes the current understanding of the conservation of mass and energy?
A) Mass is conserved; energy is not conserved.
B) Both mass and energy are separately conserved.
C) The sum of mass (times c2) and energy is conserved.
D) Physicists are still searching for a comprehensive conservation rule involving mass and energy.
190. What is nuclear fusion?
A) nucleus transforming into a nucleus of a different element by emitting an electron and a neutrino
B) removal of electrons from atoms to form ions
C) two nuclei sticking together to form a new, heavier nucleus
D) heavy nucleus splitting apart to form two lighter nuclei
191. Nuclear fusion is the
A) combining of electrons with nuclei to produce atoms and release energy.
B) splitting of heavier nuclei to produce lighter nuclei and energy.
C) combining of hydrogen atoms to produce hydrogen molecules, H2, and energy.
D) combining of light nuclei (e.g., hydrogen) to produce heavier nuclei (e.g., helium) with a resultant release of energy.
192. What is the energy source for the Sun?
A) thermonuclear fusion in the core
B) radioactive decay of the nuclei of heavy elements
C) primordial heat, left behind from when the Sun first formed
D) heat released by gravitational contraction as the Sun slowly shrinks
193. What is the main source of the energy radiated by the Sun?
A) Chemical reactions combine hydrogen and helium to produce energy.
B) Protons are destroyed and converted into pure energy as described by Einstein’s mass-energy relationship.
C) Small nuclei combine to form larger nuclei with a consequent release of energy.
D) gravitational collapse as described by the Kelvin–Helmholtz contraction
194. What process provides the power to maintain the Sun’s radiative output?
A) fission of uranium to form lead
B) fusion of hydrogen into helium
C) decay of heavy elements in the solar core and the emission of neutrinos
D) fusion of helium into carbon
195. The Sun’s source of energy at the present time is
A) thermonuclear fission (splitting) of heavy elements into hydrogen.
B) thermonuclear fusion (combination) of hydrogen atoms.
C) the chemical burning of hydrogen gas with oxygen.
D) gravitational contraction.
196. Which of these BEST describes the net fusion reaction powering the Sun?
A) 4 He O
B) 2 H He
C) 3 He C
D) 4 H He
197. In the thermonuclear process that is thought to heat the Sun, the nuclei of which chemical elements are converted to other nuclei to produce the requisite energy?
A) Helium is converted to hydrogen.
B) Iron is transformed to a series of lighter elements in chain reactions, leading eventually to hydrogen.
C) Hydrogen is converted to helium.
D) Uranium is converted to lead.
198. How much longer can the Sun continue to generate energy by nuclear reactions in its core?
A) about 5 million years
B) about 50 billion years
C) about 500,000 years
D) about 5 billion years
199. How much hydrogen is converted to helium each second in the Sun?
A) 6 billion tons
B) 600 tons
C) 6 tons
D) 600 million tons
200. Who first postulated that the interior of the Sun is millions of Kelvin?
A) Stephen Hawking
B) Albert Einstein
C) George Gamow
D) Arthur Eddington
201. The highest temperatures in the Sun are found in the
A) corona.
B) chromosphere.
C) photosphere.
D) solar interior.
202. By how much does the mass of the Sun decrease each second because of the energy radiated from it (its luminosity)?
A) 6.0 1011 kg
B) 2.0 107 kg
C) 3.9 1026 kg
D) 4.3 109 kg
203. In the 1920s, Arthur Eddington made a proposal that proved vital to showing how stars generate energy. This was that
A) the Sun’s core is much hotter than previously thought.
B) hydrogen fusion is responsible for the Sun’s energy output.
C) supernovae are responsible for the creation of heavy elements.
D) more massive stars generate energy quickly and have shorter lifetimes.
204. At the present time, the energy of the Sun is generated
A) throughout the Sun by gravitational contraction.
B) in the central core by fusion of helium nuclei and in an outer shell by fusion of hydrogen nuclei.
C) only in its central core by fission of heavy nuclei.
D) only in its central core by fusion of hydrogen nuclei.
205. What is the threshold temperature for the fusion of hydrogen to helium to occur?
A) 19,000 K
B) 153,000 K
C) 107 K
D) 1.55 107 K
206. The dominant energy source that powers the Sun at the present time is
A) the release of gravitational energy as the Sun slowly contracts.
B) thermonuclear fusion of hydrogen into helium in the core.
C) thermonuclear fission of helium into hydrogen in the core.
D) thermonuclear fusion of helium into heavier elements in the core.
207. Hydrogen “burning” by fusion reactions occurs only in the deep interior of the Sun (and other stars) because
A) the density there is sufficiently low that hydrogen atoms can collide with each other often enough.
B) this is the only place in the Sun where there is sufficient hydrogen.
C) only in the core is the temperature low enough and the density high enough to allow fusion to occur.
D) the requisite conditions of high temperature and high density occur only there.
208. How many joules of energy would be released if a U.S. penny (2.5 10–3 kg) were converted entirely to energy? The speed of light is 3 108 m/s.
A) 7.5 105
B) 2.25 108
C) 2.25 1014
D) 2.25 1017
209. A hydrogen nucleus (a proton) has a charge of +1, and a helium nucleus has a charge of +2. Why, then, does it require four protons to form helium in the core of the Sun?
A) Two of the protons are converted into neutrinos.
B) Two of the protons become neutrons.
C) Two of the protons are ejected back into the solar material.
D) Two helium nuclei are formed from the four protons.
210. The net hydrogen fusion reaction in the Sun is 4 1H 1 4He + neutrinos + energy. What forms does this energy take?
A) kinetic energy associated with the motion of the four protons
B) kinetic energy associated with the motion of the helium, protons, and gamma-ray photons
C) chemical energy associated with the electrons in orbit around the helium nucleus
D) gravitational energy associated with the attraction of the particles at close range
211. What is a positron?
A) chargeless and almost massless particle
B) nucleus of a helium atom
C) positively charged particle otherwise similar to an electron
D) nucleus of a hydrogen atom
212. A positron is a
A) hydrogen nucleus.
B) theory about which there is absolutely no doubt.
C) charged neutron.
D) Positively charged particle otherwise similar to an electron.
213. What happens to the positrons produced by the nuclear reactions in the core of the Sun?
A) The positrons combine with neutrons to form protons.
B) The positrons collide and stick together to form helium.
C) The positrons collide with electrons, producing energy.
D) The positrons escape from the Sun into space.
214. When four protons collide to form helium, what fraction of the original mass of the protons is converted into energy?
A) 0.7%
B) 100%
C) 0.05%
D) 4%
215. Which of these physical products are NOT produced by the Sun during the thermonuclear process in which hydrogen nuclei are combined together in its core?
A) heavy nuclei, such as uranium
B) positrons
C) helium nuclei
D) neutrinos
216. Apart from the helium nuclei and energy that are produced in proton-proton reactions in the Sun’s core, what are the other by-products?
A) protons, neutrinos, and electrons
B) gamma rays, negative electrons, and neutrinos
C) gamma rays and neutrinos
D) positrons, gamma rays, and neutrinos
217. Thermonuclear fusion reactions in the core of the Sun convert four hydrogen atoms into one helium atom. The helium atom has
A) an undetermined amount of mass, depending on the temperature at which the reaction occurs.
B) the same mass as the four hydrogen atoms because the mass of any product has to equal the sum of the mass of its parts.
C) less mass than the four hydrogen atoms; the mass loss is converted to energy via the equation E = mc2.
D) more mass than the four hydrogen atoms; the energy produced in the reaction appears as the extra mass from the equation E = mc2.
218. When two protons and two neutrons combine to form 4He, the helium nucleus is less massive than the sum of the four original particles used to construct it. What is the significance of this result?
A) The lost mass is transformed into energy.
B) The mass is lost through friction.
C) The lost mass can be accounted for by the masses of the particles emitted as radioactive decay during the interaction.
D) The mass disappears without a trace.
Section: 11-9
219. What stops the Sun from collapsing under the force of its own gravity?
A) The interior of the Sun is under such high pressure that it is a liquid, and liquids are incompressible.
B) Neutrinos from the Sun’s core collide with gas atoms and prevent them from falling inward.
C) Ions and electrons in the Sun are pushed apart by the electric forces between their charges.
D) The Sun is held up by gas pressure due to the very high temperature inside it.
220. To what does the term “hydrostatic equilibrium” in the Sun refer?
A) balance of gas pressure outward and magnetic forces inward
B) balance of gravity inward and gas pressure outward
C) creation of one helium nucleus for the “destruction” of every four hydrogen nuclei
D) balance of gas pressure inward and heat outward
221. The Sun has existed for a very long time without substantial change in its appearance or behavior, so it must be in hydrostatic equilibrium. Under these conditions, which two parameters must be in balance at all points throughout the Sun’s interior?
A) magnetic field and the force of gravity
B) force of gravity and outward gas pressure
C) numbers of hydrogen and helium nuclei
D) hydrogen gas pressure and helium gas pressure
222. Any object will collapse under its own weight unless something stops it. In an ordinary star like the Sun, this collapse is prevented by
A) turbulence and upwelling in the atmosphere of the star.
B) the rotation of the star, generating centrifugal force.
C) gas pressure inside the star.
D) the star’s solid core.
223. The energy transfer process that operates in the Sun via matter flows is known as
A) convection.
B) radiation.
C) thermonuclear fusion.
D) conduction.
224. What is the dominant mechanism by which energy is transported through the inner regions of the Sun?
A) hotter gas rising and cooler gas falling—convective transport of energy
B) photons transferring between nuclei and atoms—radiative transport of energy
C) neutrinos streaming outward through the Sun’s material—particle transport of energy
D) collisions of faster-moving particles with slower-moving particles—conductive transport of energy
225. What is the dominant mechanism by which energy is transported through the outer regions of the solar interior?
A) highly penetrating neutrinos streaming outward through the Sun’s material—particle transport of energy
B) photons transferring between nuclei and atoms—radiative transport of energy
C) collisions of faster-moving particles with slower-moving particles—conductive transport of energy
D) hotter gas rising and cooler gas falling—convective transport of energy
226. Of the three ways in which heat energy is transmitted from one place to another (radiation, conduction, convection), which is (are) important in carrying heat from the solar interior to the surface of the Sun?
A) radiation and convection
B) radiation alone, by photons of energy
C) conduction and convection
D) conduction, convection, and radiation
227. Energy is transported from the center of the Sun to the surface by
A) radiation in the thermonuclear core, convection everywhere else.
B) convection in the thermonuclear core, radiation everywhere else.
C) mostly convection, radiation only in the outer layers.
D) mostly radiation, convection only in the outer layers.
228. Of the three ways in which energy is transported in nature, which two are important in the Sun?
A) radiation and conduction
B) convection and conduction
C) The question is wrong; all three ways in which energy is transported are equally important in the Sun.
D) radiation and convection
229. The two most important processes by which energy is transported from the core of the Sun to the photosphere are
A) conduction and convection.
B) radiation and convection.
C) radiation and conduction.
D) radiation and neutrino emission.
230. The mechanism at work when energy is transmitted by convection is the
A) flow of hot gases.
B) fusion of hydrogen nuclei into helium nuclei.
C) successive exchange of radiant energy as photons between atoms.
D) passage of radiation through a gas at the speed of light.
231. The average time taken for energy generated by thermonuclear fusion in the center of the Sun to reach the surface layers and escape is calculated to be
A) about 200,000 years.
B) about 1 year.
C) only a few seconds.
D) about 10 million years.
232. During its existence in the Sun’s interior, a particular photon experiences
A) only one collision.
B) thousands of collisions.
C) millions of collisions.
D) collisions numbering more than millions.
233. In carrying energy through the interior of the Sun, there are many collisions between particles (photons, ions, atoms). What is the net direction of the energy flow in these collisions?
A) The collisions are random, the energy flows equally in all directions, and it is only by chance that some photons carry energy out of the Sun.
B) The collisions generally result in energy flow from the core, where temperatures are higher and the particles are moving faster, toward the outer layers where temperatures are lower and particles are moving more slowly.
C) The collisions generally result in energy flow from the core, where particles are more massive and thus carrying more energy, toward the outer layers where particles are less massive and thus carry less energy.
D) Because of the higher temperatures toward the core, the particles there are mostly ionized. The electric charge of these ionized particles repels particles from farther out from penetrating the core. Thus, energy flow is primarily outward.
234. Convection currents in the Sun’s interior occupy what fraction of the Sun’s radius?
A) outer 30% of the radius
B) inner 10% of the radius, at the core
C) whole radius
D) inner 80% of the radius
235. The order of the layers or parts of the Sun, as radius increases, is
A) radiative zone, convection zone, chromosphere, photosphere, corona.
B) radiative zone, convection zone, photosphere, chromosphere, corona.
C) corona, chromosphere, convection zone, photosphere, radiative zone.
D) radiative zone, convection zone, corona, chromosphere, photosphere.
236. Just outside the radiative zone of the Sun lies the
A) convection zone.
B) conduction zone.
C) photosphere.
D) corona.
237. The temperature at the center of the Sun, where thermonuclear processes take place, is approximately
A) 6000 K.
B) 1.5 million K.
C) 1.5 107 K.
D) 4500 K, as shown by sunspots.
238. The temperature of the Sun throughout its radius and including its atmosphere
A) is almost constant from the center to the surface but falls abruptly above the visible surface.
B) decreases outward from the center but then increases again in the atmosphere.
C) decreases smoothly outward from the center, gradually merging at the “top” of the atmosphere into the cold of the interplanetary medium.
D) increases and decreases several times between the center and the surface, then decreases through the atmosphere.
239. Where is most of the mass of the Sun concentrated?
A) spread uniformly throughout the Sun
B) in the convective zone
C) in the photosphere
D) in the inner core
240. The core of the Sun, in which the Sun’s thermonuclear energy is produced, takes up about
A) 1/2 the Sun’s radius.
B) 1/4 of the Sun’s radius.
C) less than 1/100 of the Sun’s radius.
D) 1/10 of the Sun’s radius.
241. According to the theoretical model of the Sun shown graphically in Figure 11-23 in the text, where is the vast majority of solar energy generated?
A) within 0.60, or 60%, of a solar radius of the Sun’s center
B) throughout the whole Sun
C) within 0.25, or 25%, of a solar radius of the Sun’s center
D) within 0.8, or 80%, of a solar radius of the Sun’s center
242. Figure 11-23 in the text shows that all of the Sun’s luminosity is generated within the inner 25% of the solar radius. What is true of the correlation of the other graphs in the figure with the luminosity graph?
A) Almost all of the Sun’s mass is located within the inner 25% of the solar radius also.
B) The core has a temperature of 15.5 106 K, the temperature needed for hydrogen fusion, throughout this inner 25% of the solar radius.
C) The temperature actually peaks in the convection zone, driving the convection process.
D) The density is greatest within the inner 25% of the solar radius, causing the high pressure and temperature required for hydrogen fusion.
243. Which of these would NOT be true if the Sun were more massive?
A) The Sun would be bluer.
B) Compression would make the Sun smaller.
C) The Sun’s surface would be hotter.
D) Earth’s orbital period would be shorter.
Section: 11-10
244. The young Sun had a core containing less helium and more hydrogen than it has now. Which of these was NOT true of the young Sun, compared with the present Sun?
A) The young Sun was less massive than the Sun is at present.
B) The young Sun was cooler in its core than the Sun is at present.
C) The young Sun was less luminous than the Sun is at present.
D) The young Sun had a smaller radius than the Sun does at present.
245. What is the “faint young Sun paradox”?
A) By observing other stellar nebula similar to what astronomers believe our solar nebula looked like, it was determined that those stars were much brighter much earlier than predictions for the Sun.
B) Theories predict that the young Sun was faint. This would have allowed many comets to escape being vaporized at perihelion, and the impact rate on the Moon and similar bodies would have been much heavier than it was.
C) The Sun has become more luminous over time, but its temperature has remained relatively constant.
D) Earth has evidence of liquid surface water dating back 4.2 billion years, but the young Sun at that time was not luminous enough to have heated Earth sufficiently to prevent water from freezing.
246. The Sun has nearly the same temperature today that it had 4.5 billion years ago, but it is now 30% more luminous. Why?
A) The Sun has a stronger magnetic field today.
B) The Sun has a larger surface area today.
C) The Sun has more sunspots today.
D) Energy took longer to escape the young Sun.
247. Which of these is MOST directly responsible for the slow increase of the Sun’s luminosity over time?
A) The increasing concentration of heavy elements in the Sun’s convective zone.
B) The slow contraction of the Sun.
C) The gradual transformation of positively charged particles to neutral particles in the Sun’s core.
D) The gradual increase of the Sun’s magnetic field.
Section: 11-11
248. What have neutrino observatories revealed about the Sun?
A) The radiative zone is bigger than first expected.
B) The Sun’s magnetic field reverses polarity every 22 years.
C) Fusion occurs via the CNO cycle.
D) Fusion occurs at about the rate expected from theoretical models of the Sun’s interior.
249. Which of these particles or types of radiation will provide the MOST direct information on the processes of nuclear fusion that are occurring at the present time in the solar core?
A) X-rays from the solar corona
B) protons in the solar wind and from solar flares
C) neutrinos
D) visible light from the photosphere